1. Technical Field
The present disclosure relates to a rotor, a manufacturing method of the rotor, and a DC motor (direct current motor) including the rotor.
2. Description of the Related Art
Traditionally, various devices such as automotive electrical components and office equipment employ a permanent-magnet DC motor as a motor serving as a power source. The permanent-magnet DC motor includes a stator onto which a permanent magnet is fixed and a rotor supported by a shaft rotatably relative to the stator. In this motor, the rotor is rotated by switching a direction of an electric current flowing through a winding wound around the rotor. Examples of a winding method (circuit structure) of the winding encompass a Y-connection method (Y-connected circuit) and a delta connection method (delta-connected circuit). In the Y-connection method, a resistance becomes higher than in the delta connection method. Therefore, a configuration employing a rotor of the Y-connection method consumes less electric current than a configuration employing a rotor of the delta connection method. Therefore, some DC motors to be integrated into battery-driven devices employ the rotor including the Y-connected winding (the rotor of the Y-connection method).
The rotor of the Y-connection method has an electrical neural point. The electrical neural point is formed by, for example, twisting together ends of the winding wound around a core and connecting the ends to each other by soldering or the like. Alternatively, the electrical neural point may be formed by connecting, to a metallic part (hereinafter, referred to as a “conduction plate”), an end of a winding wound around a core by, e.g., welding or soldering (see JP-A-63-156563). Note that some rotors of the delta connection method may also include the conduction plate.